1. Field of the Invention
The present invention relates to a rolling bearing device that supports an axle of a railroad vehicle, etc.
2. Related Art
As a bearing device that rotatably supports an axle of a railroad vehicle, there is, for example, a rolling bearing device including a double-row tapered roller bearing at an end of the axle, and sealing units disposed outside axial opposite ends of the tapered double-row tapered roller bearing.
FIG. 4 is a partial sectional view showing an example of a conventional rolling bearding device to be used for a railroad vehicle. This rolling bearing device 100 has an inner ring 101 that is externally fitted to an axle S, an outer ring 102 fixed to the vehicle, a tapered roller 103 disposed between the inner and outer rings 101 and 102, and a sealing unit 104 for sealing a gap between the inner and outer rings. The sealing unit 104 has a seal case 105 fixed to the outer ring, and a sealing member 106 that is held in the seal case 105 to seal a gap formed along with the axle S. The seal case 105 is fixed to an end of the outer ring 102, and has a tubular fixed portion 105a that is fixedly pressed-fitted into an inner periphery of a shoulder 102a of the outer ring 102, and a tubular holding portion 105b that extends outward of the outer ring 102 from the fixed portion 105a, and holds the sealing member 106 axially outside an end face of the outer ring 102.
Further, a protruding portion 105c that protrudes radially outward is formed at an end of the fixed portion 105a. The protruding portion 105c is engaged with a seal groove 102b formed in the shoulder 102a, thereby regulating axial movement of the seal case 105. (See, for example, JP-A-2003-269471.)
In the rolling bearing device in the above conventional example, the sealing unit 104 is configured such that a gap between the seal case 105 and the axle S is sealed by the sealing member 106, and a gap between the seal case 105 and the outer ring 102 is sealed by the surface contact between an inner peripheral surface of the shoulder 102a of the outer ring 102, and an outer peripheral surface of the fixed portion 105a that is press-fitted to the inner peripheral surface.
However, as described above, since the contact between the seal case 105 and the outer ring 102 is surface contact, there is a possibility that a slight gap may be formed therebetween due to a difference in surface roughness, etc.
Moreover, if the seal case 105 co-rotates with the rotation of the axle S, this co-rotation may cause the seal case 105 to rotate relative to the outer ring 102. As a result, there is a probability that the outer peripheral surface of the fixed portion 105a and the inner peripheral surface of Shoulder 102a are rubbed mutually and worn, and a gap may be formed therebetween.
As described above, if a gap is formed between the seal case 105 and the outer ring 102, dust, etc. may enter the inside of the rolling bearing device, or grease inside the bearing device may leak out, and thereby the durability of the rolling bearing device may be deteriorated. For this reason, measures of that enhance the sealing performance between the outer ring 102 and the seal case 105 are expected.